Galley, Sink Cabinet, Part 7: Reinforcing the Fiberglass Sink

The forward side of the sink, reinforced with biaxial cloth
Many galley sinks on many fiberglass boats manufactured over the past forty or fifty years are not made of stainless steel, but are instead, like the boat itself, made of fiberglass. This is especially true of those boats that are fitted with fiberglass hull liners. Makes sense, right? If the manufacturer is going to make a cabinet out of fiberglass by means of a mold, why would he not also make a sink for this cabinet in the same manner? Fiberglass is lightweight and strong, especially when laid up thick with cloth or when reinforced with core material of some sort, such as balsa or plywood. The galley cabinet on the Ericson 25 is stout, consisting of both cored material and multiple layers of fiberglass cloth. The galley sink, on the other hand, is somewhat less stout, consisting of a thin layer of glass, covered with a single layer of chopped strand fiberglass mat for reinforcement. On the galley sink of my boat, someone at the Ericson yard did not apply the chopped strand mat in an even fashion. Consequently, one part of one side of the galley sink was weak and brittle. I discovered this weak spot in the midst of the modifications that I was making to the sink cabinet. Knowing that I needed to address this problem, I digressed from the primary task at hand to fix it. This posting, therefore, on my reinforcement of the fiberglass sink on Oystercatcher, my Ericson 25, serves as the seventh of twelve in my series on the modifications I made to this cabinet for the purpose of converting this previously wasted space into a functional area for the storage of plates, bowls, glasses, and other items.
The galley sink and cabinet as they appeared at the time of purchase
There are at least three Ericson 25s, which I have seen, that have stainless steel sinks in place of the original fiberglass ones. We see one example below. I don't know whether the owners installed these stainless sinks on account of problems that they had with the original ones, or they simply switched to stainless for the sake of appearances. I must admit that the stainless steel gives the galley a more classy look, and I will say that I myself contemplated switching to stainless for this reason.
Ultimately, I opted to stick with the fiberglass original for one reason. I liked the fact that the original contained a lip around its rim. This lip resembled the lip around the rim of the adjacent ice box, and it was clearly intended to support a cover or lid similar to that seen on the icebox. As I said in an earlier posting, that lid on the icebox was not original to the boat. I suspect that, at one time, there were pieces of mahogany that served as lids for both the icebox and the sink. At any rate, what was it about this lip that I found appealing? Well, it was the fact that it could support a lid. Why would a lid be appealing to me? I'll tell you why. With a lid in place, this area of the counter could serve as an excellent step of sorts for climbing in and out of the companionway when the air conditioner box was in place.
In case you haven't seen my article on my construction of this air conditioner box, here's a picture of it as seen from the cockpit.
 Here's a view from inside.
To climb into the boat, you sit on top of the box, put one foot on the sink countertop and the other foot on the top rung of the ladder. To climb out, you essentially do everything in reverse. You can see in the picture below that I have placed a piece of plywood over the sink temporarily to act as a step during this dry-fitting of the air conditioner box.
As I said in my last posting, I had vigorously wiped the inside of the cabinet with xylene in preparation for the sealing of the joints. Much of the area around the sink had wax on it from the mold, back when this boat was manufactured in 1975.
It was during my rubbing of the bottom of the sink and the sides of the sink with xylene that I first noticed the problem spot, i.e., the weak spot where there was no chopped strand mat to support the thin fiberglass.
During most of the refitting of this boat, I had used the sink for the storage of pencils, pens, and small tools. I had never noticed what looked like a small piece of white caulk on the forward side of the sink (the side here pictured on the left).
Somehow I had also never noticed this lump of caulk during the visits I had made to the boat at the time of purchase.
I pulled the caulk away and shined a light against the side of the sink. This was what I saw. It did not look like a puncture mark. Instead it looked like a crack.
But how did it crack? My best guess was this - someone grabbed the side of the sink and used it for a handhold when making his or her way through the main salon toward the companionway. It made a perfect handhold, or so it seemed. The crack was right where my finger tips dug into the side of the sink.
Take a look at the picture below of the sink after it had been reinforced. In the pictures that will follow, you will be looking into the narrow space between the sink and the top edge of the cut-out.
Here, I've circled the problem area. You can see that there is no chopped strand mat on this side of the sink.
A close-up. This area was fragile. It easily flexed with just a little bit of pressure from my index finger.
Before I attempted a repair, I wanted to find out if the sink had other problem areas of which I was unaware. I had never used the sink as a sink, so this was an important task. I figured that if I filled the sink with water I could easily discovery any problem.
One little problem that I need to solve before doing this experiment with the water involved finding a rubber stopper for the sink. I had thrown the old one away soon after purchasing the boat. It was ruined from dry-rot. I measured the drain hole and then went to a hardware store and bought what I thought was the right-sized stopper. I could not tell for sure, since the stopper was tapered and it was encased in plastic. Was it the right size? Of course not. One more trip back and forth.
The right-sized stopper: 1-1/8 inch.
With the stopper in place, I filled the sink with one gallon of water.
I did not detect any leaks anywhere. The light revealed that this side was thin and not very strong. I pressed all the other sides forcefully with my hands. They were sturdy.
I did not want to fill the sink with any more than one gallon. I estimated that the sink would hold a little over three gallons. I could tolerate removing one gallon of water with a sponge. I didn't like the thought of removing three gallons worth.
Before I removed the water, I took this picture of the underside of the sink. The drain pipe was bone dry. This was good. No leaks around the fittings.
With the water removed, I began to prep the side of the sink for reinforcement. I began by again wiping this area repeatedly with xylene.
You can see in the picture below that the wax on the side of the sink is detectable by the sheen on its surface.
I used 12 ounce biaxial cloth for the reinforcement job.
Two layers of this seemed to me to be sufficient. Biaxial is strong, and it absorbs much more epoxy than regular fiberglass cloth.
After scuffing the surface of the fiberglass with sandpaper, I did one final wipe down with xylene.
I wet out the side of the sink with neat epoxy and then applied the first layer of biax. This I wet out with a brush. Afterwards, I applied the second layer, which I also fully wet out with the brush. Then, into the pot of epoxy that remained I mixed colloidal silica. When it had reached a ketchup-like consistency, I picked up the brush yet again and this time applied the slightly thickened epoxy. I did this for the purpose of filling in the weave of the biax. This would strengthen the repair, and it would result in a relatively smooth surface that would make for much easier sanding.
A couple of days later, after the epoxy had cured, I returned with my quarter-sheet sander and my Rockwell Sonicrafter oscillating tool with its sanding head attached.
I also used my long time favorite - the Dremel, with the right-angle attachment and the drum-shaped sanding wheel. As always, this tool was very helpful in tight spaces and along sharp edges. The high speed of the drum made for easy work along these edges.
The biaxial cloth after it was fully sanded. When I tested the repair, I was pleased to find that there was now very little flex in this formerly flimsy and fragile area of this fiberglass sink. This was an unwanted digression from the primary task at hand, but it was a necessary one. When it was over, I was glad that I had taken the time to do it, and to do it right.
This ends this seventh of twelve postings on the modifications I made to the galley sink cabinet of Oystercatcher, my Ericson 25.

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